It is known that material may form or build up in vessels of the circulatory system; such material may seriously compromise the health of the patient. For example, thrombi or blood clots may form and may partially or completely occlude a blood vessel, decreasing or even completely cutting off blood flow through the vessel. The thrombus may adhere to the vessel wall or may be dislodged, becoming free floating in the vessel. A free floating thrombus, also known as an embolus, may travel along a vessel and eventually cause a blockage in a distant part of the body, such as the heart or the brain, with potentially lethal consequences.
Various devices are known for capturing and removing thrombi and other objects from a patient's blood system. Such devices typically involve the use of a plurality of different tools which are deployed in different stages of the capture and removal procedure. For example, a first medical device may be introduced to break the thrombus into pieces so as to prevent it from blocking a vessel. However, breaking the thrombus into pieces can be harmful to the patient as dislodged parts may travel through the circulatory system and eventually block another vessel elsewhere. In order to avoid this, blocking and/or suction means are required to ensure that the dislodged parts are safely collected. For example, a filter may be positioned distal of the thrombus so as to catch the dislodged parts after the thrombus has been broken up by the first medical device. The material trapped by the filter can remain in place until removed using yet further apparatus such as an aspirator. Various prior art thrombus capturing devices are disclosed in US2010/0249815, U.S. Pat. No. 7,621,870, US 2007/0149996 and U.S. Pat. No. 7,780,696.